Yes, many gamers have not moved to the Xbox 360 and continue to play Halo 2. Others have, indeed, moved to the Xbox 360 but continue to play Halo 2 in "Backwards Compatability" mode or have their old Xbox "180" connected for playing.
Bungie didn't release much information about these halo 2 maps:
"There are a ton of details we simply can’t reveal right now but we can confirm that this content will be coming out sometime next Spring and it will cost something to download. We can also confirm that this new content is only going to be available on Xbox 360 and that you’ll need a hard drive to download them (which is also required to play Halo 2 on 360 anyways)."
Why release new Halo 2 maps so close to a Halo 3 release? Well, given that Halo 3 will be publically beta tested in Spring 2007 it's clear that the release will not be in the spring of that same year (else testing would occur sooner). Is this meant to hold us all over?
This might just be a method to get Halo 2 players to commit a few more dollars to some downloadable content? Details are slim to none on the cost, if any, for the new maps. The only sure thing: It is currently Xbox 360 only. That means you need to be playing on the 360's version of Halo 2 in compatiblity mode to gain access to these maps. This may change, but Bungie has stated it is not their call. Microsoft Game Studios has the final say on all Halo content, so that means Microsoft will tell the world if old Xbox players will have these maps in the future.
Bungie mentioned backwards compatability bugs/glitches and stated that they may go back and revist the game port to the 360 to make sure its bug free for the new map content, since its currently a 360 only release.
source: bungie.net
